Conventionally, an injector according to Patent Literature 1 includes a stator core that generates an attractive force while a coil is energized, and a movable core that is attracted by the stator core and moves together with a valve body. An electric controller controls an energization of the coil to open the injector. The electric controller controls a time that the injector is being opened, that is, the electric controller controls an injection time of the fuel injected into the internal combustion engine which is equivalent to an injection quantity. The electric controller switches between a voltage of a battery and a boost voltage that is the voltage of the battery boosted by a booster circuit, in the energization of the coil.
When the attractive force is greater than a valve-opening force that is a force obtained by adding the fuel pressure in the injector to an elastic force of an elastic component such as a spring in the injector, the injector is opened. The electric controller executes a control to increase a current flowing through the coil to a peak current value that is a current value that is predetermined, by applying the boost voltage to the coil. Then, the electric controller executes a control to control an average value of the current flowing through the coil at a pickup current value that is lower than the peak current value, by a duty control that alternatively energizes and deenergizes the coil by the voltage of the battery. The attractive force exceeding the valve-opening force is generated by executing the above control, and the injector is opened.
Since the fuel pressure pressing in a direction to suppress the movable core decreases while the fuel is injected when the injector is opened, the attractive force that is less than the valve-opening force can be generated and held. The electric controller executes a control to control the average value of the current flowing through the coil at a holding current value that is a current value that is predetermined, by executing the duty control. The holding current value has a magnitude that is less than the pickup current value and is used to generate the attractive force sufficient to hold the opening of the injector.